Biomedical subjects
Publications and source records attributed to L C Logan.
We describe a case of Echo 11 virus infection producing a moderately severe conjunctivitis in a laboratory worker who had handled infected material. This virus has previously been known to cause systemic disease, sometimes fatal, in children.
The relative virulence and immunogenicity of type 1 (T1) and type 3 (T3) cells of Neisseria gonorrhoeae were determined by tests with two different kinds of subcutaneous chambers in guinea pigs. In tests with a tissue nonencapsulated (NE) chamber, T1 gonococci were found to be greater than 1000 times more virulent as well as about 1000 times more immunogenic than T3 cells of the same gonococcal strain. However, T1 and T3 cells were found to be equally virulent for a tissue encapsulated (TE) chamber in guinea pigs. Analysis of fluids from the two types of chambers in a complement-dependent bactericidal assay revealed that the NE chamber fluid contained a substantially higher level of complement activity than fluid from TE chambers. The decline in complement level of chamber fluids due to tissue encapsulation was also confirmed by quantitation with rocket gel electrophoresis. A greater resistance of T1 cells to the bactericidal effects of complement appeared to provide a mechanism by which the T1 cells were most virulent than T3 cells for subcutaneous chambers in guinea pigs. Consequently, the NE chamber implant would appear to provide a more relevant environment for studying the virulence, as well as immunological characteristics of gonococcal strains and experimental immunogens.
An in vivo typing system for studying the immunological relationship of gonococcal strains was established. Nine gonococcal strains of proven virulence for guinea pig subcutaneous chambers were selected, and these isolates were used to immunize groups of guinea pigs that were subsequently cross-challenged with graduated numbers of gonococci from these isolates. Resistance to infection was determined by culture of fluid from challenged chambers; results were expressed as the median dose, in colony-forming units, of gonococci required to produce infection in each group of immunized guinea pigs. This information was then used to develop immunotypes of gonococci based on the cross-protection results obtained. Four cross-protecting immunotypes were established from the preliminary nine strains tested.
Strains of gonococcus were shown to be immunologically heterologous. Serum bactericidal activity generally correlated with induced immunity to gonococcal challenge as detected by the guinea pig subcutaneous chamber model. Sera devoid of bactericidal activity reflected the lack of cross-protection in subcutaneous chambers. Factors affecting the bactericidal assay described in this report include (i) source of complement, (ii) concentration of test antigen and complement activity, and (iii) presence of calcium and magnesium ions and bovine serum albumin in diluent. Poor correlation was observed between agglutinating activity of the immune sera and protection.
Reference materials were produced to standardize the immunoglobulin class specificity and potency of immunofluorescent anti-IgM conjugates used for diagnostic tests for congenital syphilis. In attempting to mimic essential immunologic characteristics of syphilitic and nonsyphilitic infant sera, we evaluated these sera in comparison with processed adult sera. We were quite surprised to discover that some syphilitic babies do not produce significant quantities to IgM antibody to T. pallidum in response to their infection, as would be expected; instead, they make relatively large amounts of IgM anti-IgG. We found this to be true also for newborns and infants infected with cytomegalovirus, rubella, and toxoplasmosis. To our knowledge, this observation has not been previously reported. However, it could have been predicted from the knowledge that older infants and young children normally produce IgM antibodies to maternal IgG allotypes (Gm factors). We are disturbed that these findings suggest that currently recommended indirect immunofluorescence IgM tests for perinatal infection may not be disease specific. Our observations may be important for a better understanding of basic immunologic mechanisms of fetal-maternal to tolerance and fetal response to life-threatening infection.
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In studies of several hundred sera, a passive-hemagglutination technique with soluble antigen of sonically treated gonococci as the sensitizing material for tanned erythrocytes and Neisseria sicca sonically treated material as an absorbent detected gonococcal antibodies in 77% of males and 88% of females infected with uncomplicated gonorrhea. However, 6% of the sera from individuals in celibate religious orders and 18% of the sera from a group of females having cervical cultures negative for gonococci were also reactive with this procedure. Erythrocytes sensitized with an alkaline extract of gonococci reacted with 23% of the sera from infected males, 49% of the sera from infected females, and 2% of the sera from celibate females.
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An automated, quantitative microhemagglutination assay for antibodies to Treponema pallidum was developed by using T. pallidum-sensitized erythrocytes and an automatic serial-dilution instrument. Reactivity was found in sera from 54 rabbits and 6 chimpanzees infected with T. pallidum. Reactivity was also found in sera from animals infected with T. pertenue, T. carateum, and T. cuniculi. No reactivity was found in sera from 75 normal rabbits or from 129 rabbits immunized with cultivatable treponemes or a variety of other bacteria. In approximately 3 min, 13 twofold serial dilutions of each of 8 preabsorbed sera and the addition of sensitized erythrocytes to each dilution were accomplished automatically. The automated assay can serve as a research tool in quantitating antibodies to pathogenic treponemes, and evaluation of its clinical usefulness seems warranted.
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Two hundred forty-five sera submitted to the Center for Disease Control, Atlanta, Ga., (CDC) were analyzed serologically in an attempt to demonstrate the diagnostic value of the Treponema pallidum immobilization (TPI) test when performed in addition to the fluorescent treponemal antibody-absorption (FTA-Abs) test. Diagnoses for the patients whose sera were tested were based on information supplied by the referring physicians. Fifty-four per cent of the diagnostic problems were resolved merely by the finding of a negative result with the FTA-Abs test. There was agreement between the serologic results of the referring laboratory and those of the CDC for 76% of sera tested by the Venereal Disease Research Laboratory test and for 71% of sera tested by the FTA-Abs test. For patients with treponemal disease, the sensitivity of the TPI test was 56% and that of the FTA-Abs test was 78%. When the FTA-Abs test was reactive, a negative TPI test was not significantly associated with systemic lupus erythematosus (P > 0.6) or other collagen vascular disease (P > 0.6), nor was a positive TPI test associated with treponemal disease (P > 0.09). It is concluded that once the result of the FTA-Abs test is known, the TPI test does not provide additional diagnostic information.